Log cutting apparatus

ABSTRACT

Apparatus for cutting logs, such as tree trunks, into lengths comprising a frame, a pair of spaced substantially parallel shafts rotatably mounted on the frame, and a pair of blade members mounted on the shafts so that a log can be fed between the blades. The blades are rotated in relatively opposite directions so that during a log cutting stroke, the blades move toward each other and into a log therebetween so as to cut substantially entirely through the log. fluid actuated cylinder assembly drives the blades through the cutting stroke. The blades are configured so that they will follow the path of least resistance during cutting movement into a log and the apparatus is particularly adapted for inclusion in a tree harvesting machine which converts standing trees into logs of predetermined length.

United States Patent 1 I Propst Dec. 4, 1973 LOG CUTTING APPARATUS [76] Inventor: Robert L. Propst, 2347 Londonderry Ave., Ann Arbor, Mich. 48104 [22] Filed: Apr. 10, 1972 [21] Appl. No.: 242,731

Primary Examiner-J. M. Meister Att0rneyOlsen and Stephenson [57] ABSTRACT Apparatus for cutting logs, such as tree trunks, into lengths comprising a frame, a pair of spaced substantially parallel shafts rotatably mounted on the frame, and a pair of blade members mounted on the shafts so that a log can be fed between the blades. The blades are rotated in relatively opposite directions so that during a log cutting stroke, the blades move toward each other and into a log therebetween so as to cut substantially entirely through the log. fluid actuated cylinder assembly drives the blades throughthe cutting stroke. The blades are configured so that they will follow the path of least resistance during cutting movement into a log and the apparatus is particularly adapted for inclusion in a tree harvesting machine which converts standing trees into logs of predetermined length.

9 Claims, 8 Drawing Figures NIL o [P I 1LT? 30 11 PATENTEDUEC 4:915

7 3,776,083 SHEET 38F 4 ime. 5

PAIENIEDBH: 4 1975 SHLET l (J? 4 LOG CUTTING APPARATUS CROSS REFERENCE TO COPENDING APPLICATION The log cutting apparatus of this invention is of the same general type, namely, employs counter rotating blades, as that shown in my prior copending patent application Ser. No. 56,583 filed July 20, 1970.

BACKGROUND OF THE INVENTION In the pulp wood industry, there is a need for apparatus which will efficiently cut logs into lengths and which will also operate over a prolonged service life with a minimum of maintenance attention. This need is for both fixed position cutting apparatus which is installed at the mill for cutting logs delivered to the mill into lengths and for portable apparatus which can be readily incorporated in a timber harvesting machine for cutting logs in the field into lengths. It is an object of the present invention, therefore, to provide improved log cutting apparatus capable of these uses.

SUMMARY OF THE INVENTION The log cutting apparatus of this invention consists of a frame which can either be incorporated in a timber harvester machine or can be mounted in a fixed position. The frame supports a pair of substantially parallel shafts which are spaced apart a distance adequate for a tree to be fed between the shafts in a direction perpendicular to the shafts. A pair of blade members having cutting ends are mounted on the shafts so that on rotation of the shafts in relatively opposite directions, the blade members are movable toward each other to positions in which the cutting ends are adjacent each other. This blade movement is obtained by actuating a hydraulic cylinder assembly so as to extend the assembly and thereby apply the necessary forces to the blade members to move them through a log to be-cut. During such movement of the blade members through the log, the log is being fed between the shafts in the direction in which the blades are moving as they rotate. Thus, in the apparatus of this invention, the log to be cut can be continuously fed between the blades and blade movement does not interfere with continuous log movement. Furthermore, the blades are configured so that during their movement into the tree they follow the path of minimum resistance in the tree to thus enable construction of the blades in a minimum thickness and size and to also allow for a minimum amount of driving energy to penetrate the log fibers. A pair of meshing gears are mounted on the shafts to insure the continuous desired relative positions of the blades. This arrangement enables the use of a small drive motor for driving one of the gears when the blades are being returned to ready positions prior to the next cut and while the hydraulic cylinder is in neutral with the fluid tank. The log cutting apparatus of this invention can thus be used in a variety of installations, both fixed and portable, for efficiently cutting logs wherein feeding of the logs is a necessary or desirable part of the system.

Further objects, features and advantages of this invention will become apparent from a consideration of the following description, the appended claims, and the accompanying drawing in which:

FIG. 1 is a fragmentary side elevational view of a timber harvesting machine which includes the log cutting apparatus of this invention;

FIG. 2 is a perspective view of thelog cutting apparatus of this invention showing the apparatus in a ready position for cutting a log;

FIG. 3 is a fragmentary sectional view of a portion of the apparatus of this invention;

FIG. 4 is a bottom view of the apparatus of this invention showing the blades in position at the conclusion of a cutting stroke; 7

FIG. 5 is an elevational view of the apparatus shown in FIG. 4;

FIG. 6 is a diagrammatic view illustrating the relative positions of the cutting blades and the drive arms therefor in the apparatus of this invention, showing the cutting blades in ready positions;

FIG. 7 is a diagrammatic view like FIG. 6 showing the blades in positionsat the end of a cutting stroke; and

FIG. 8 is an elevational view of a cutting blade in the apparatus of this invention.

With reference to the drawing, the log cutting apparatus of this invention, indicated generally at 10, is shown in FIG, 1 incorporated in a timber harvesting machine 12 which includes a vehicle 14 having a tree severing andprocessing assembly 16 mounted on the forward end thereof. The assembly 16 consists of a main frame 18 on which a mast 20 is mounted and which supports a log severing unit 22. A pair of tree gripping and feeding assemblies 24, the details of which form no part of the present invention, are mounted on a pair of vertically spaced platform members 25 that are rotatably mounted on an upper portion of the mast 20. The assemblies 24 are capable of moving a tree, such as the one shown at 26, between a severing station disposed above the severing unit 22 and a processing station disposed above a log storage rack 28 on the main frame 18. The assemblies 24 are also capable of moving a tree up and down relative to the mast 20.

The apparatus 10 consists of a frame 30 which is supportedon the main frame 18 in the harvester 12 by the mast 20 and an adjusting cylinder 31'. It is to be under stood, however, that the frame 30 can be mounted in a fixed position in a mill or the like in which apparatus other than the gripping and feeding assemblies 24 are employed for feeding'the tree 26 past the frame 30. A pair of shaft assemblies 32 (FIGS. 2 and 4) 'are mounted on the frame 30 in substantially horizontal spaced relation so that they are perpendicular to the tree 26 in the processing station. A pair of blade members 34 having cutting ends 36 and hub ends 38 are mounted on the shaft assemblies 32 by means of plates 40. The hub ends 38 of the blade, members 34 are in the form of angle members secured to and extended between the plates 40. Bolts 42 extend through slots 44 in the blade members 34 to adjustably mount the blades 34 on the hub ends 38. Backup plates 46 on the plates 40 have curved edges 48 that engage the blades 34 on the backsides adjacent the cutting ends 36. The plates 46 thus strengthen the blades 34 and enable the blades 34 to apply the necessary cutting forces to the tree 26 without a requirement that the blades be constructed of a size such that the power required to drive them be too high. 1

A pair of gear members 50 are mounted on the shafl assemblies 32 to one side of the blades 34. The gears 50 mesh with each other and function at all times to maintain the blades 34 in predetermined relative positions. At their outer ends, the shafl assemblies 32 are secured to drive arms 52. Each drive arm 52 is secured at one of its ends 54 to a shaft assembly 32 so that pivotal movement of the drive arm 52 will provide for rotation of the shaft assembly 32. Pivot members 56 extend through the opposite ends 58 of the arms 52.

One of the pivot members 56 is secured to a stirrup member 60 and the other pivot member 56 is secured to another stirrup member 62. The stirrup member 60 is mounted on the cylinder member 64 for a hydraulic cylinder assembly 66 having a piston rod 68. The terminal end of the piston rod 68 is secured to the other stirrup 62. The cylinder assembly 66 is thus operable, on extension, to rotate the blades 34 through a portion of a circle.

The blades 34 are rotatable through a full circle or cycle from the ready positions shown in FIG. 2 in which the blades face each other and are disposed on opposite sides of a log 26 to be cut. As shown in FIGS. 6 and 7, when the blades 34 are rotated in relatively opposite directions from the ready positions shown in FIG. 6 to the position shown in FIG. 7 in which the ends 36 are adjacent each other and slightly overlap, the blades 34 have been jointly moved entirely through the tree 26 so as to sever the tree. The necessary power for forcing the blades 34 through the tree 26 is obtained by the cylinder assembly 66 in the following manner. As shown in FIG. 6, in the ready positions of the blades, the drive arms 52 are inclined downwardly from the shaft assemblies 32 toward each other and the cylinder assembly 66 is retracted. When the cylinder assembly 66 is extended, as shown in FIG. 7, to move the drive arms 52 to positions extending downwardly and outwardly, the blades 34 are rotated through the arcs necessary to move them through the tree and into the overlapped positions shown in FIG. 7. This movement of the blades from the ready position to the overlapped position is sometimes hereinafter referred to as the cutting stroke of the blades.

A drive gear 70 (FIGS. 4 and meshes with one of the gears 50 and is driven by a hydraulic motor 72 mounted on the frame 30. After the cylinder assembly 66 has been extended to move the blades 34 through the cutting stroke and to the position shown in FIG. 7, a valve (not shown) is opened to relieve the hydraulic pressure in the cylinder assembly 66, and the motor 72 is operable to rotate the drive gear 70 so as to complete the rotation of the blades 34 and return them to their ready positions shown in FIG. 6.

In the operation of the apparatus 10, assume that the blades 34 are in the ready positions illustrated in FIG. 1 and that a tree gripping and feeding assembly 24 is operating to move a tree 26 downwardly between the blades 34. When the lower end of the tree 26 engages a switch actuating member 76, mounted on the log storage rack 28, the cylinder assembly 66 and the drive gear 70 are actuated resulting in extension of the assembly 66. When the cylinder assembly 66 is extended, the blades 34 are rotated toward each other so that they are moved into the tree 26 to the positions shown in FIG. 7 in which the blades have severed the tree. During severing of the tree, there is no interruption in the downward movement of the tree 26 since the ends 36 of the blades that are doing the cutting are moving in the same direction that the tree 26 is moving. The curvature of the blades 34 is plotted to follow the path of least resistance through the tree, the blades doing the minimum amount of tree fiber compressing in an up and down direction as the blades 34 cut through the tree. As shown in FIG. 8, the curvature of the blade 34 becomes less acute in a direction extending from the cutting end 36 to the hub end 38. Thus, the angle A between the surface of the blade near the cutting end 36 and a fixed plane 78 is greater than the angle B of the blade surface at a location between the ends 36 and 38. This blade configuration enables cutting of the tree with a minimum power requirement for moving the blades 34 and with a minimum size blade 34.

Once the cutting stroke has been completed, so that the blades 34 are in the positions shown in FIG. 7, the hydraulic pressure in the cylinder assembly 66 is relieved, and the drive gear 70 takes over and continues the rotation of the blades 34 in relatively opposite directions so as to return the blades 34 to the ready posi tions shown in FIG. 1. During the time that the drive gear 70 is rotating the blades 34, the cylinder assembly 66 is connected to tank so that it has no power effect on movement of the blades 34. During such blade movement, the tree gripping and feeding assembly 24 operates to continue to feed the tree 26 downwardly. The initial log length cut from the lower end of the tree 26 is stored in the rack 28 and when the lower end of the severed tree hits the switch actuating member 76, the above cycle is repeated. The cycle is continuously repeated until the entire tree 26 has been cut into log lengths disposed in the rack 28.

From the above description it is seen that this invention provides log cutting apparatus which can be readily and efficiently incorporated in a timber harvesting machine 12. In addition, the frame 30 can be supported in a fixed position for cutting log lengths in any environment in which such cutting is desired. In such case, the shaft assemblies 32 on which the blades 34 are supported can be positioned in vertically spaced positions as well as the horizontally spaced positions shown in FIG. 1. It is only necessary to feed a log through the space between the blades 34 in order to obtain efficient cutting of the log.

What is claimed is:

1. In timber harvester apparatus which includes a frame and means for feeding a tree downwardly past said frame, tree cut-ofiapparatus on said frame operable to cut said tree into lengths, said cut-ofi apparatus comprising a pair of blades mounted on opposite sides of said tree for rotation about axes generally perpendicular to said one direction, each of said blades being curved between the ends thereof to enable the blade to follow the arcuate path of least resistance during cutting movement into a downwardly moving tree and terminating in a cutting end, means for repeatedly rotating said blades in relatively opposite directions through a cycle in which each blade is rotated full circle, and means connected to and extending between said blades continuously maintaining said blades in predetermined relative positions so that during each cycle the blades are moved through a tree cutting stroke in which the blades move from facing positions on opposite sides of said tree in arcuate paths into said tree from opposite sides thereof into positions in which said ends are adjacent each other and have jointly been moved substantially entirely through said tree so as to sever the tree. 2. Apparatus according to claim 1 wherein said means for feeding a tree and said means for rotating said blades operate concurrently during movement of said blades through a tree cutting stroke.

3. Apparatus according to claim 1 further including shaft means supporting said blades for rotation, arms attached to said shaft means, and contractible and expansible fluid actuatable cylinder means connected to and extending between said arms, said cylinder means being extensible to drive said blades through said cutting stroke. 7

4. Apparatus for cutting logs comprising a frame, a pair of spaced substantially parallel shaft means rotatably mounted on said frame, a pair of blade members having cutting ends and hub ends, said blade members having their hub ends mounted on said shaft means so that on rotation of said shaft means in relatively opposite directions said blade members are movable toward each other to positions in which said cutting ends are adjacent each other, each of said blades being curved between the ends thereof with the curvature thereof being progressively less in a direction from the cutting end toward the hub end to enable the blade to follow the arcuate path of least resistance during cutting movement into a moving log.

5. Apparatus for cutting logs comprising:

a frame,

a pair of spaced substantially parallel shaft assemblies rotatably mounted on said frame,

a pair of blade members mounted on said shaft assemblies,

a fluid actuated cylinder assembly having a cylinder and a piston rod extending therefrom,

a pair of drive arms connected to said shaft assemblies and to said cylinder and piston rod so that on relative movement of said piston rod and said cylinder, said shaft assemblies are rotated to in turn rotate said blade members, said blade members being movable during each full circle rotation thereof through a cutting stroke commencing with the blade members arranged in a facing spaced relation and concluding with said blade members extending toward each other so that the cutting ends thereof are adjacent each other.

6. Apparatus according to claim 5 in which the blade members are rotated through an angle of substantially during a cutting stroke, said arms and blades being relatively arranged so that the blades are movable through said cutting stroke in response to movement of said arms from positions inclined away from each other.

7. Apparatus according to claim 6 wherein said piston rod is extended with respect to said cylinder to move said arms to in turn provide for movement of said blade members through said cutting stroke.

8. Apparatus according to claim 6 further including gear members on said shaft assemblies arranged in a meshing relation at positions to one side of said blade members so as to maintain said blade members in predetermined relative positions during rotation thereof. I

9. Apparatus according to claim 8 further including a drive gear positioned in driving meshing engagement with one of said gear members, and means for rotating said drive gear to in turn rotate said gears so as to rotate said shaft assemblies and said blade members. 

1. In timber harvester apparatus which includes a frame and means for feeding a tree downwardly past said frame, tree cut-off apparatus on said frame operable to cut said tree into lengths, said cut-off apparatus comprising a pair of blades mounted on opposite sides of said tree for rotation about axes generally perpendicular to said one direction, each of said blades being curved between the ends thereof to enable the blade to follow the arcuate path of least resistance during cutting movement into a downwardly moving tree and terminating in a cutting end, means for repeatedly rotating said blades in relatively opposite directions through a cycle in which each blade is rotated full circle, and means connected to and extending between said blades continuously maintaining said blades in predetermined relative positions so that during each cycle the blades are moved through a tree cutting stroke in which the blades move from facing positions on opposite sides of said tree in arcuate paths into said tree from opposite sides thereof into positions in which said ends are adjacent each other and have jointly been moved substantially entirely through said tree so as to sever the tree.
 2. Apparatus according to claim 1 wherein said means for feeding a tree and said means for rotating said blades operate concurrently during movement of said blades through a tree cutting stroke.
 3. Apparatus according to claim 1 further including shaft means supporting said blades for rotation, arms attached to said shaft means, and contractible and expansible fluid actuatable cylinder means connected to and extending between said arms, said cylinder means being extensible to drive said blades through said cutting stroke.
 4. Apparatus for cutting logs comprising a frame, a pair of spaced substantially parallel shaft means rotatably mounted on said frame, a pair of blade members having cutting ends and hub ends, said blade members having their hub ends mounted on said shaft means so that on rotation of said shaft means in relatively opposite directions said blade members are movable toward each other to positions in which said cutting ends are adjacent each other, each of said blades being curved between the ends thereof with the curvature thereof being progressively less in a direction from the cutting end towaRd the hub end to enable the blade to follow the arcuate path of least resistance during cutting movement into a moving log.
 5. Apparatus for cutting logs comprising: a frame, a pair of spaced substantially parallel shaft assemblies rotatably mounted on said frame, a pair of blade members mounted on said shaft assemblies, a fluid actuated cylinder assembly having a cylinder and a piston rod extending therefrom, a pair of drive arms connected to said shaft assemblies and to said cylinder and piston rod so that on relative movement of said piston rod and said cylinder, said shaft assemblies are rotated to in turn rotate said blade members, said blade members being movable during each full circle rotation thereof through a cutting stroke commencing with the blade members arranged in a facing spaced relation and concluding with said blade members extending toward each other so that the cutting ends thereof are adjacent each other.
 6. Apparatus according to claim 5 in which the blade members are rotated through an angle of substantially 90* during a cutting stroke, said arms and blades being relatively arranged so that the blades are movable through said cutting stroke in response to movement of said arms from positions inclined away from each other.
 7. Apparatus according to claim 6 wherein said piston rod is extended with respect to said cylinder to move said arms to in turn provide for movement of said blade members through said cutting stroke.
 8. Apparatus according to claim 6 further including gear members on said shaft assemblies arranged in a meshing relation at positions to one side of said blade members so as to maintain said blade members in predetermined relative positions during rotation thereof.
 9. Apparatus according to claim 8 further including a drive gear positioned in driving meshing engagement with one of said gear members, and means for rotating said drive gear to in turn rotate said gears so as to rotate said shaft assemblies and said blade members. 